1. Field of the Invention
The present invention relates to a zinc-oxide-based target containing zinc oxide as a predominant component.
2. Background Art
Transparent conductive film finds a wide range of applications, including IR-shielding sheet, electrostatic shielding sheet, electroconductive film (sheet heater, touch switch, etc.), and transparent electrodes employed in a display device or a similar device, and demand for such transparent conductive film has increased. Conventionally, such transparent conductive film has been made of tin-doped indium oxide (ITO) film, which is an expensive material. Therefore, there is keen demand for inexpensive transparent conductive film.
Under such circumstances, zinc-oxide-based transparent conductive film, which is less expensive than ITO film, has become attractive. Currently, aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), etc. are available on the market.
Since zinc-oxide-based transparent conductive film is inferior to ITO in conductivity and stability, a variety of elements are added to zinc oxide in order to improve conductivity and stability (see Japanese Patent Application Laid-Open (kokai) Nos. 62-154411, 9-45140, 2002-75061, 2002-75062, etc. (Claims)). Among such additional elements, addition of Ga has been extensively studied (see Japanese Patent Application Laid-Open (kokai) Nos. 10-306367, 11-256320, 11-322332, etc. (Claims)).
However, zinc-oxide-based transparent conductive film has excessively high etching rate, making patterning of the film difficult, and is unsatisfactory in terms of environmental durability. These problems impede practical use of zinc-oxide-based transparent conductive film.